On Wed, May 26, 2021 at 6:57 AM Daniel P. Berrangé <berrange@redhat.com>
wrote:

> On Tue, May 25, 2021 at 12:37:21PM -0700, Doug Evans wrote:
> > Hi.
> >
> > I want to confirm the command line syntax y'all want for ipv6 host
> > forwarding.
> >
> > IIUC, the command line syntax is required to be consistent with the use
> of
> > "ipv6=on|off" elsewhere.
> > Can you confirm that's correct?
> >
> > If so, how does one apply "ipv6=on" to the "::60022-:22" hostfwd spec in
> > the following example:
> >
> > $ qemu-system-x86_64 [...] --nic
> user,id=n1,model=e1000,hostfwd=::60022-:22
> >
> > ?
>
> Probably easier if we start from the HMP  hostfwd_add command which takes
>
>   hostfwd_add  ::60022-:22
>
> With that, adding the flags is obvious
>
>   hostfwd_add  ::60022-:22,ipv6=on|off,ipv4=on|off
>


Data point:

There's been discussion of supporting ipv6->ipv4 and ipv4->ipv6.
If we want to provide for this then the ipv4/6 flags need to apply to the
host/guess address.

E.g.,

hostfwd_add ::60022,ipv6=on-:22,ipv4=on
[for ipv6->ipv4]


> IIUC, that can be handled in the slirp_hostfwd() method impl.
>
> The question is then how this works on the CLI. IIUC ,the "hostfwd=XXX"
> ARG value is passed to slirp_hostfwd() eventually, so the change for
> the HMP parsing will "just work".
>
> The complication is that the comma is ambiguous between the --net arg
> parsing, and the hostfwd parsing. So you would end up having to escape
> the commas (ie replace , with ,,):
>
>  --nic user,id=n1,model=e1000,hostfwd=::60022-:22,,ipv6=on,,ipv4=on
>
> If you forget to escape the commas, then the flag ends up applying
> to the --nic instead, where ipv4/ipv6 are indeed value for other
> reasons.
>
> This kind of sucks, but that's where we are with the old fashioned
> design of --nic parsing
>
>
> Not sure if someone else has better ideas here ?
>
>